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Tag: VLC

One of the subjects I blog about, is a computer I named ‘Plato’, which is running Debian / Stretch (Debian 9), and the desktop manager of which is Plasma 5, which is the successor to KDE 4.x .

One of the features which KDE 4 definitely had, was an icon in the notification-tray, from which we could control our volume levels easily, as well as to mute the sound temporarily, eventually to be unmuted again, at which point the earlier, unmuted settings should be remembered. At first glance it would seem that Plasma 5 has done away with this capability. Trying to solve this can cause people to spend hours searching the Internet, changing their Plasma 5 preferences, and maybe even forgetting their Plasma 5 preferences, because they disabled all their System Sounds from there.

Recently, I was on a fact-finding mission about this, and am willing to share my solutions.

Under Plasma 5, we really only need to have 2 packages installed, in order to control our volume-levels, etc., assuming that we have gotten our hardware recognized first. Those packages would be:

‘plasma-pa’

‘pavucontrol’

The first of these packages integrates with Plasma, and is also responsible for the icon in the notification tray. The second package gives us more control, over our sound-levels specifically, since Plasma 5 uses the Pulse Audio sound-server by default.

If we can see the icon in the notification tray, then a detail which we may overlook after we left-click on that icon, is a tiny little loudspeaker-symbol, on the left end of one of the volume sliders:

Left-clicking on this little symbol will cause the volume-bar to the right of it to become slightly pale, which will mean, that the device in question has been muted. I’m saying that ‘we’ could overlook that we even have this feature, because earlier, ‘I’ did not know that I have this feature.

But, this is only what the ‘plasma-pa’ package can show us. The ‘pavucontrol’ package gives us the ability to fine-tune our sound-levels as shown below:

Now, there’s an aspect to how this setup now works, which is slightly more complicated than how KDE 4 used to handle it. The Pulse Audio server attempts to adjust playback as well as recording levels, on a per-application basis. Thus, the view above is almost empty, because there were no applications playing back any sounds, at the moment I recorded this screen-shot.

A frustrating fact which can exist with this, is that some applications will only play a sound for 2 seconds, during which an additional volume-bar appears in the GUI, and after which that volume-bar disappears again, even if we did not have enough time to adjust one volume level. This happens to result from the design-decision, that volume-control should exist at the per-application level. Hence, even if we use media-control keys on our keyboard, those keys will only affect the one main application which happens to be playing, at any given moment. They won’t affect System Sounds.

But this description might sound like I have to say, ‘There is no problem,’ when in fact, under Debian / Stretch, There Is a problem. That problem, as I see it, lies in the fact that by default, the one volume-bar which the GUI has shown above, for all System Sounds, may not even work.

I have written numerous postings, to guide myself as well as anybody else who might be interested, on the subject of Video-DVD burning, as well as on the subject of Video-Blu-ray burning. According to advice which I gave, it’s possible to use a program named “tsMuxerGUI”, to create the Blu-ray File Structure, which a Blu-ray playback-device will play.

According to additional advice I gave, it’s possible to burn these Blu-rays using some version of ISO-13346, which is also known as ‘UDF’, as opposed to burning them with ISO-9660, as the File System with which data is encoded on the disk.

But what I have noticed, is that certain Blu-rays which were burned in this way, will not play back using the application “VLC”. Normally, the open-source player named VLC can play back Blu-rays, which were commercially produced. So, it would seem natural, that we’d want to test our Blu-rays on the computer we used to create them, with the VLC application as the playback system.

My own experience has been, that the Blu-rays which result play back fine on my Sony Blu-ray playback-device, but do not open on VLC, on my computers.

As unlikely as this may seem, I did after all return to the conclusion, that I’ve created two UDF-encoded Blu-rays, which VLC cannot read, because of the customized UDF-encoding.

Apparently, when we instruct VLC to play a disk inserted into a specific Blu-ray drive, such as perhaps ‘/dev/sr1′, VLC expects to connect directly with the drive, rather than to use the mount-point exclusively, which Linux can create for us.

This is somewhat bewildering, because by default, I need to mount the disk in question, as a regular user, which we can do from the notification tray, before VLC is capable of playing it. But then, whether VLC can in fact read the Blu-ray turns into an independent question, from whether Linux was able to mount it for the rest of the computer to use.

(Edit 10/23/2017 :

There is an even more improbable-sounding possibility, as to why this actually happens. It may be that VLC expects to be able to access the Media Key Block of an inserted Blu-ray Disk, in order to decrypt that, and to start playing back DRM-ed Blu-rays. This would require not only raw access to the disk, but also that such a Block be present on the disk.

If I translate this problem into Human Logic, I’ll get, that ‘VLC’ is only capable of playing Blu-rays that have DRM, when those Blu-rays are also ISO9660-compatible. This may be unfortunate, because even though UDF 2.50 is still not ‘the law of the land’, ISO9660-compatibility may be phased out one day, while DRM likely will not be. )

But there is a workaround. VLC includes in its menus, the ability to Play A Directory. We can choose this option, and can navigate to the mount-point, which we created when we mounted the disk from the notification tray. That mount-point should exist under the directory ‘/media’ , have ‘BDMV’ as one of its sub-folders. And when we then direct VLC to play the folder, that is the parent folder to the ‘BDMV’ sub-folder, we are in fact directing it to play the root-folder of the disk.

And in my own, recent experience, VLC is then able to play the disk. I specifically took care, not to direct VLC to play the folder on my HD, from which I created one of the Blu-rays, but rather the folder that is the mount-point of an actually-inserted disk. Because, it would be pointless to conduct a test, which physically bypasses the disk.